The present invention relates to a mounting block assembly which incorporates a detachable and replaceable wear collar member for rotatably supporting a cutter bit within such block. Heretofore, such cutter bits have included the type generally known as conical bits or pik-bits of the type used for construction and excavation applications. For example, such cutter bits are generally utilized with such mounting blocks which are detachable or fixably mounted on an excavating wheel of a trenching machine or on the drive wheel of a road scarifying machine or the like. Such cutter bits are illustrated, for example in U.S. Pat. Nos. 3,841,708 and 4,201,421.
Heretofore, there has been a need to mount such cutter bits in a rotatable relationship relative to the blocks so as to minimize wear between the component parts while permitting easy assembly and replacement of the parts when necessary. It is especially important to minimize the wear on the mounting blocks themselves as their cost for replacement is relatively high compared to the replacement cost of the bits. It will be recognized, however, that it is also important to minimize, to the greatest extent possible, wear on the bits since a relatively substantial number of bits are required for each such excavating machine and oftentimes a full set of bits (i.e. 500 or more) are replaced after merely a few hours of operation due to damage and/or wear. In addition, it is important to support and stabilize the bit to the greatest extent possible so as to promote the generally concentric uniform rotational movement of the bit relative to the block thereby to promote uniform wear on the bit. In this case, it will be recognized that such uniform wear increases the overall wear-life of the bit.